1. Field of the Invention
The present invention relates to a substrate for an electro-optical device, an electro-optical device and an electronic device, and a method for manufacturing the electronic device, and more specifically, to the construction of an electro-optical device in which a metal layer is provided on a substrate.
2. Description of the Related Art
In general, in various electro-optical devices, such as a liquid crystal display device, an organic electro-luminescent device, and a plasma display device, a pair of electrodes is opposite to each other with an electro-optical layer interposed therebetween, and a substrate is provided on at least one side of the electro-optical layer. A liquid crystal display device, which is an example of an electro-optical device, usually has a panel in which electrodes are formed on the inner surfaces of a pair of substrates, the pair of substrates is bonded to each other by a sealing material, and liquid crystal is injected in a space surrounded by the pair of substrates and the sealing material.
There are two reflecting types of liquid crystal display devices: one is a reflective liquid crystal display device, and the other is a transflective liquid crystal display device, both having a reflective plate or reflective layer. As this type of device, a device in which a reflective layer is disposed on the external side of a substrate is used. However, in this case, since light passes through a substrate two times and is then visually recognized, display quality deteriorates due to parallax caused by the path of light. Therefore, it is common that an internal reflection type device having a reflective layer on the inner surface of the substrate is mainly manufactured.
In the internal reflection type liquid crystal display device, the reflective layer is formed by depositing a metal material, such as aluminum, an aluminum alloy, a silver alloy, or a chromium alloy, on the substrate using an evaporation method or a sputtering method. In the case of color liquid crystal display devices, color filters have a construction in which colored layers are provided on the reflective layer. In this case, there has been known a method of preventing the reflective layer from damaging by covering the reflective layer with the colored layers and by forming the reflective layer within the boundary narrower than that of the colored layers.
An example of the transflective liquid crystal display device will be described with reference to FIG. 16. A liquid crystal display device 200 has a construction in which a liquid crystal layer 235 is provided between a first substrate 210 and a second substrate 220. In the first substrate 210, a transparent base layer 212, a reflective layer 213, colored layers 214F and 214C, a protective layer 215, a transparent electrode 216, and an alignment film 217 are formed in order on a substrate 211. In the second substrate 220, a transparent electrode 222 and an alignment film is formed in order on a substrate 221. An opening 213a is formed corresponding to every pixel P in the reflective layer 213. A light transmission region Pt is formed of the opening 213a, and a light reflection region Pr is formed of regions other than the light transmission region Pt. A light-shielding layer 214 is formed between pixels. According to the liquid crystal display device, it is possible to make the liquid crystal layer 235 thicker in the light transmission region Pt and to make the liquid crystal layer 235 thinner in the light reflection region Pr only by patterning the protective layer 215. Also, according to the conventional embodiment illustrated in FIG. 16, it is possible to reduce the difference of display quality between transmissive display and reflective display by making the optical density of the colored layer 214C in the light transmission region Pt larger and the optical density of the colored layer 214F in the light reflection region Pr smaller.
FIG. 17(a) is an enlarged cross-sectional view illustrating the construction of a part of the peripheral region provided on the outside of a display region in which a pixel P is arranged in the first substrate 210 of the liquid crystal display device 200.
In the peripheral region, a light-shielding layer 214BM is formed by laminating a red colored layer 214R and a blue colored layer 214B in order. The light-shielding layer 214BM is covered with a protective layer, on which a wiring line 218 to be connected to the transparent electrode 216 is arranged. An outer periphery 213e of the reflective layer 213 is provided under the light-shielding layer 214BM.
However, the liquid crystal display device 200 may have a defect in display in that the outer periphery 213e of the reflective layer 213 lifts together with the light-shielding layer 214BM to disconnect the wiring line 218 as illustrated FIG. 17(b) when the reflective layer 213, the colored layers 214B, 214R, and 214G, the protective layer 215, the electrode 216, and the wiring line 218 are formed in this order. Such a defect in display occurs even when the reflective layer is formed to be narrower then the colored layer, resulting in a reduction of yield.
Accordingly, the present invention is designed to solve the above problems, and it is an object of the present invention to provide a substrate for an electro-optical device and the construction of the electro-optical device capable of reducing a defect in display due to the disconnection of wiring lines and of improving the yield of product by preventing the lifting of the outer periphery of metal layer.